Novel dyes containing a substituted 2-pyrazolin-5-one nucleus

ABSTRACT

NOVEL MEROCYANINE AND OXONOL DYES ARE PROVIDED WHICH FEATURE A 3-ARYLAMINO OR A 3-LOWER FATTY ACID AMIDO SUBSTITUTED 2-PYRAZOLIN-5-ONE NUCLEUS. MEROCYANINE DYE SALTS OF THE INVENTION SENSITIZE DIRECT POSITIVE PHOTOGRAPHIC SILVER HALIDE EMULSIONS.

nited States Patent 3,743,640 NOVEL DYES CONTAINING A SUBSTITUTEDZ-PYRAZOLIN-S-ONE NUCLEUS Frank G. Webster, Rochester, N.Y., assignor toEastman Kodak Company, Rochester, N.Y.

No Drawing. Original appplication Sept. 8, 1967, Ser. No. 666,512, nowPatent No. 3,579,344, dated May 18, 1971. Divided and this applicationJune 22, 1970, Ser.

Int. Cl. C09b 23/10 US. Cl. 260-2402 8 Claims ABSTRACT OF THE DISCLOSURENovel merocyanine and oxonol dyes are provided which feature a3-arylamino or a 3-lower fatty acid amido substituted 2-pyrazolin-5-onenucleus. Merocyanine dye salts of the invention sensitize directpositive photographic silver halide emulsions.

This application is a division of my copending application Ser. No.666,512, filed Sept. 8, 1967, now US. Patent 3,579,344.

This invention relates to novel photographic materials, and moreparticularly to a new class of merocyanine and oxonol dyes, to directpositive silver halide emulsions containing certain of these new dyes,and to photographic elements prepared with such emulsions.

In one important aspect, this invention is directed to the provision ofnovel dyes which function as effective electron acceptors in directpositive emulsions. The class of dyes of this invention would not beexpected to function as sensitizers in direct positive emulsions, sincethe closely related dyes of British Pat. 544,645 are sensitizers fornegative emulsions. Such prior art dyes do not function as efiicientelectron acceptors in direct positive emulsions. This class of dyes isespecially useful, since they provide good sensitization to shorterwavelength radiation, particularly to blue and, in some cases, to greenradiation. The dyes of the invention are particularly effective inreduction and gold fogged emulsions of the type described in BritishPat. 723,019.

It is, accordingly, an object of this invention to provide a new classof improved and novel, direct positive photographic silver halideemulsions, and more particularly fogged emulsions of this type,containing at least one of the novel dyes of the invention. Anotherobject of this invention is to provide novel emulsions as abovecontaining, in addition, a photographic color former. Another object ofthis invention is to provide novel lightsensitive photographic elementscomprising a support material having thereon at least one layer of thenovel emulsions of the invention. Another object of this invention is toprovide novel merocyanine and oxonol dyes. Still another object of thisinvention is to provide novel filter dyes. Other objects of thisinvention will be apparent from this disclosure and the appended claims.

I have now found that certain merocyanine quaternary salt dyescontaining a 3-arylamino, or 3-lower fatty acid amido substitutedZ-pyrazolin-S-one nucleus are outstanding electron acceptors, and insome instances are spectral sensitizers, in direct positive typephotographic silver halide emulsions. They provide superior reversalsystems, especially with fogged direct positive silver halide emulsionsthat are characterized by both good speed and desired selectivesensitivity to radiation in the blue or green region of the spectrumwith maximum sensitivity occurring in the region of less than 525 nm.The images produced with these new direct positive photographicemulsions are clear and sharp, and of excellent contrast. Thecorresponding unquaternized mercocyanine and certain oxonol dyes of theinvention, I have further found, function primarily as useful filterdyes in photographic filter layers.

The novel merocyanine and oxonol dyes of the invention comprise firstand second 5- to 6-membered nitrogen containing heterocyclic nucleijoined by a linkage such as a double bond or a methine bridge, at leastone of said nuclei being a 3-arylamino or a 3-lower fatty acid amidosubstituted Z-pyrazolin-S-one nucleus joined at the 4-carbon atomthereof to said linkage; and said second nucleus being joined at acarbon atom thereof to said linkage to complete said dye.

The preferred merocyanine quaternary salt dyes of the invention that areespecially useful as electron acceptors and sensitizers for directpositive photographic silver halide emulsions are represented by thefollowing general formula:

(L) I, Z

NH-R3 wherein n and m each represents a positive integer of from 1 to 2;L represents a methine linkage, e.g., CH-, C(CH -C(C H etc.; Rrepresents an alkyl group, including substituted alkyl (preferably alower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl,propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc., andsubstituted alkyl groups (preferably a substituted lower alkylcontaining from 1 to 4 carbon atoms), such as a hydroxyalkyl group,e.g., B-hydroxyethyl, w-hydroxybutyl, etc., an alkoxyalkyl group, e.g.,B- methoxyethyl, w-butoxybutyl, etc., a carboxyalkyl group e.g.,fi-carboxyethyl, w-carboxybutyl, etc., a sulfoalkyl group, e.g.,p-sulfoethyl, w-sulfobutyl, etc., a sulfatoalkyl group, e.g.,fl-sulfatoethyl, w-sulfatobutyl, etc., an acyloxyalkyl group, e.g.,fi-acetoxyethyl, 'y-acetoxypropyl, w-butyryloxybutyl, etc., analkoxycarbonylalkyl group. e.g., B-methoxycarbonylethyl,w-ethoxycarbonylbutyl, etc., or an aralkyl group, e.g., benzyl,phenethyl, etc., and the like; an alkenyl group, e.g., allyl,l-propenyl, 2-butenyl, etc., and the like; R represents a group givenfor R or any aryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl,chlorophenyl, etc.; R represents an alkyl group e.g., methyl and ethylor an aryl group, e.g., phenyl, tolyl, xylyl, naphthyl, methoxyphenyl,cyanophenyl, nitrophenyl, chlorophenyl, 2,5-dichlorophenyl,2,4,6-trichlorophenyl, etc.; R represents an aryl group, e.g., phenyl,tolyl, xylyl, naphthyl, methoxyphenyl, cyanophenyl, nitrophenyl,chlorophenyl, 2,5-dichlorophenyl, 2,4,6-trichlorophenyl,p-fluorosulfonylphenyl, etc., or an acyl group, e.g. COR wherein R is analkyl group containing from 1 to 4 carbon atoms, e.g., methyl, ethyl,propyl, isopropyl, butyl, etc. (which substituents form a 3-lower fattyacid amido substituted 2-pyrazolin-5-one nucleus); X represents an acidanion, e.g., chloride, bromide, iodide, thiocyanate, sulfamate,perchlorate, p-toluenesulfonate, methyl sulfate, ethyl sulfate, etc.,and Z represents the nonmetallic atoms necessary to complete asensitizing or a desensitizing heterocyclic nucleus containing from 5 to6 atoms in the heterocyclic ring, which nucleus may contain a secondhetero atom such as oxygen, sulfur, selenium or nitrogen, such as thefollowing nuclei: a thiazole nucleus, e.g., thiazole, 4-methylthiazole,4-phenylthiazole, S-methylthiazole, S-phenylthiazole,4,5-dimelhylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)thiazole,benzothiazole, 4-chlorobenzothiazole, 4- or S-nitrobenzothiazole, 5-chlorobenzothiazole, 6 chlorobenzothiazole, 7 chlorobenzothiazole,4-methylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole,d-nitrobenzothiazole, 5- bromobenzothiazole, 6-bromobenz/othiazole,5-chloro-6- nitrobenzothiazole, 4 phenylbenzothiazole, 4methoxybenzothiazole, S-methoxybenzothiazole, 6-meth'oxybenzothiazole, Siodobenzothiazole, 6 iodobenzothiazole, 4-ethoxybenzothiazole,S-ethoxybenzothiazole, tetrahydrobenzothiazole,5,6-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole,S-hydroxybenzothiazole, 6-hydroxybenzothiazole, a-naphthothiazole,fi-naphthothiazole, {3,5 naphthothiazole, 5methoxy-flfi-naphthothiazole, 5-ethoXy-B-naphthothiazole,8-methoxy-a-naphthothiazole, 7-methoxy-u-naphthothiazole,4'-methoxythianaphtheno 7',6',4,5 thiazole, nitro group substitutednaphthothiazoles, etc.; an oxazole nucleus, e.g., 4-methyloxazole, 4nitro-oxazole, 5 methyloxazole, 4 phenyloxazole, 4,5-diphenyloxazole,4-ethyloxaz0le, 4,5-dimethoxazole, s-phenyloxazole, benzoxazole,S-chlorobenzoxazole, S-methylbenzoxazole, 5-phenylbenzoxazole, 5- or 6-nitrobenzoxazole, S-chloro-6-nitrobenzoxazole, 6-methylbenzoxazole, 5,6dimethylbenzoxazole, 4,6 dimethylbenzoxazole, 5 methoxybenzoxazole, 5ethoxybenzoxazole, S-chlorobenzoxazole, 6-methoxybenzoxazole,S-hydroxybenzoxazole, 6-hydroxybenzoxazole, a-naphthoxazole,p-naphthoxazole, nitro group substituted naphthoxazoles, etc.; aselenazole nucleus, e.g., 4-methylselenazole, 4-nitroselenaz0le,4-phenylselenazole, benzoselenazole, 5- chlorobenzoselenazole,S-methoxybenzoselenazole, S-hydroxybenzoselenazole, 5- or6-nitrobenzoselenazole, 5- chloro 6 nitrobenzoselenazole,tetrahydrobenzoselenazole,, a-naphthoselenazole, fl-naphthoselenazole,nitro group substituted naphthoselenazoles, etc.; a thiazoline nucleus,e.g., thiazoline, 4-methylthiazoline, 4-nitrothiazoline, etc.; apyridine nucleus, e.g., 2-pyridine, 5- methyl-Z-pyridine, 4-pyridine,3-methyl-4-pyridine, nitro group substituted pyridines, etc.; aquinoline nucleus, e.g., 2-quinoline, 3-rnethyl-2-quinoline,5-ethyl-2-quinoline, 6- chloro-2-quinoline, 6-nitro-2-quinoline,8-chloro-2-quinoline, 6-methoXy-2-quinoline, 8-ethoxy-2-quinoline, 8-hydroxy-2-quin0line, 4-quinoline, 6-methoxy-4-quinoline, 6-nitro-4-quinoline, 7-methyl-4-quinoline, 8-chloro-4-quinoline,l-isoquinoline, 6-nitro-1-isoquinoline, 3,4-dihydro-1- isoquinoline,3-isoquinoline, etc.; a 3,3-dialkylindolenine nucleus, preferably havinga nitro or cyano substituent, e.g., 3,3-dimethyl-5 or 6-nitroindolenine,3,3-dimethyl-5- or 6-cyanoindolenine, etc.; and, an imidazole nucleuse.g., imidazole, l-alkylimidazole, 1-alkyl-4-phenylimidazole,l-alky1-4,5-dimethylimidaz0le, benzimidazole, l-alkylbenzimidazole,l-aryl-S,6-dichlorobenzimidazole, l-alkyla-naphthimidazole,l-aryl-B-naphthimidazole, l-alkyl-S- methoxy-u-naphthimidazole, or, animidazo[4,5-b] quinoxaline nucleus, e.g., 1,3 dialkylimidazo[4,5-b]quinoxaline such as 1,3-diethylimidazo [4,5-b1quinoxaline,6-chloro-1,3-diethylimidazo[4,5-b]quinoxaline, etc., 1,3-dialkenylimidazo[4,5-b]quinoxaline such as1,3-diallylimidazo[4,5-b]quinoxaline, 6 chloro-1,3-diallylimidazo[4,5-b1quinoxaline, etc., 1,3-diarylimidazo[4,5-b]quinoxaline such asl,3-phenylimidazo[4,5-b]quinoxaline, 6- chloro 1,3diphenylimidazo[4,5-b]quinoxaline, and the like. Nuclei wherein Zcompletes an imidazo [4,5-b1quinoxaline nucleus, or a nitro groupsubstituted thiazole, oxazole, selenazole, thiazoline, pyridine,quinoline or imidazole nucleus are desensitizing nuclei. From theforegoing, it will be apparent that Z constitutes the atoms necessary tocomplete a heterocyclic nitrogen containing nucleus of the type used inthe production of merocyanine and oxonol dyes. The dyes of Formula Iwherein R represents an aryl group have shown greater speed and arepreferred.

The merocyanine dyes of the invention defined above are powerfulelectron acceptors and spectral sensitizers for direct positivephotographic silver halide emulsions. In addition, they are also usefuldesensitizers in emulsions used in the process described in Stewart andReeves, U.S. Patent No. 3,250,618, issued May 10, 1966.

As used herein desensitizing nucleus refers to those nuclei which, whenconverted to a symmetrical carbocyanine dye and added to gelatin silverchlorobromide emulsion containing 40 mole percent chloride and 60 molepercent bromide, at a concentration of from 0.01 to 0.2 gram dye permole of silver, cause by electron trapping at least about an percentloss in the blue speed of the emulsion when sensitometrically exposedand developed three minutes in Kodak developer D-19 at room temperature.Advantageously, the desensitizing nuclei are those which, when convertedto a symmetrical carboc'yanine dye and tested as just described,essentially completely desensitize the test emulsion to blue radiation(i.e., cause more than about to loss of speed to blue radiation).

The unquaterm'zed merocyanine dyes and the oxonol dyes of the inventionthat are primarily useful as filter dyes in photographic layers andelements are represented by the following general formulas:

wherein n, m, R, R R and Z are as previously defined, and d represents apositive integer of from 1 to 3. x

The merocyanine dyes and quaternary salts thereof defined by Formulas Iand II, wherein m is 2, can be prepared in a number of ways. Forexample, they can be conveniently prepared by heating a mixture of (l) aheterocyclic compound of the formula:

(Iv) z R,-r 'I =oH-on ..-,-o-R, X

wherein n, R X and Z are as previously defined, and R represents methyl,ethyl, benzyl, etc., and (2) a 2-pyrazolin-S-one compound of theformula:

(V) RrIITG=O N =L--NHR wherein n, R, X and Z are as previously defined,and R represents an aryl group, e.g., phenyl, tolyl, etc., inapproximately equimolar proportions, in the presence of a condensingagent such as a trialkylamine, e.g., triethylamine, etc., piperidine,N-meth'ylpiperidine, etc., in an inert solvent medium such as aceticanhydride, etc. The crude dyes of Formula 11 above are then separatedfrom the reaction mixtures and purified by one or morerecrystallizations from appropriate solvents such as hot pyridine, etc.The purified dyes are next converted to the corresponding quaternarysalts of Formula I above by heating with appropriate quaternizingreagents such as dimethylsulfate, methyl p-toluenesulfonate, etc.,followed by cooling and one or more recrystallizations.

The dyes and salts of Formulas I and II above can also be prepared byreacting (1) a compound of the formula:

wherein n, R, X and Z are as previously defined, and R representsacetanilidovin'yl group w,hich (2) a compound of the formula:

(VII) R -lII----C=O i NH-R;

wherein R and R are as previously defined, followed by quaternization,under substantially similar reaction conditions as above described.

To prepare the dyes and salts defined by Formulas I and II above,wherein m is 1, a convenient method comprises heating a mixture of (1) acompound of the formula:

wherein n, R. X and Z are as previously defined, and R represents analkylthio group, e.g., methylthio, ethylthio, etc., or an arylthiogroup, e.g., phenylthio, etc.; and (2) a compound defined by Formula VIIabove, followed by quarternization, under substantially similar reactionconditions as above described.

The oxonol dyes of the invention defined by Formula HI above areconveniently prepared by condensing approximately 2 moles of a compoundof Formula VII above with one or more moles of, for example,diethoxymethyl acetate (forms monomethine oxonol dyes, i.e., thosewherein d is 1), or 1,1,3-trimethoxypropene (forms trimethine oxonoldyes, i.e., those wherein d is 2), or glutaconic aldehyde dianilhydrochloride (forms pentathine oxonol dyes, i.e., those wherein d is3), in the presence of a condensing agent such as tirethylamine, in aninert solvent medium such as ethanol, at refluxing temperatures of thereaction mixture. After the reaction is substantially completed, thecrude dye compounds are separated, precipitated in water acidified withhydrochloric acid and purified by one or more recrystallizations fromappropriate solvents such as methanol.

In accordance with this invention, I prepared my new class of improvedand novel, direct positive photographic silver halide emulsions byincorporating one or more of the cyanine dyes of Formula I above of theinvention into a sutable fogged silver halide emulsion. The emulsion canbe fogged in any suitable manner, such as by light or with chemicalfogging agents, e.g., stannous chloride, formaldehyde, thiourea dioxideand the like. The emulsion may be fogged by the addition thereto of areducing agent such as thiourea dioxide and a compound of a metal moreelectropositive than silver such as a gold salt, for example, potassiumchloroaurate as described in British Pat. 723,019 (1955).

Typical reducing agents that are useful in providing such emulsionsinclude stannous salts, e.g., stannous chloride, hydrazine, sulfurcompounds such as thiourea dioxide, phosphonium salts such astetra(hydroxymethyl) phosphonium chloride, and the like. Typical usefulmetal compounds that are more electropositive than silver include gold,rhodium, platinum, palladium, iridium, etc., preferably in the form ofsoluble salts thereof, e.g., potassium chloroaurate, auric chloride (NHQPdCl and the like.

Useful concentrations of reducing agent and metal compound (e.g., metalsalt) can be varied over a considerable range. As a general guideline,good results are obtained using about .05 to 40 mg. reducing agent permole of silver halide, and 0.5 to 15.0 mg. metal compound per mole ofsilver halide. Best results are obtained at lower concentration levelsof both reducing agent and metal compound.

The concentration of added dye can vary widely, e.g., from about 50 to2000 mg. and preferably from about 400 to 800 mg. per mole of silverhalide in the direct positive emulsions.

As used herein, and in the appended claims, fogged refers to emulsionscontaining silver halide grains which produce a density of at least 0.5when developed, Without exposure, for 5 minutes at 68 F. in KodakDeveloper DK-SO having the composition set forth below, when theemulsion is coated at a silver coverage of 50 mg. to 500 mg. per squarefoot.

DEVELOPER G. N-methyl-p-aminophenol sulfate 2.5 Sodium sulfite(anhydrous) 30.0 Hydroquinone 2.5 Sodium metaborate 10.0 Potassiumbromide 0.5

Water to make 1.0 l.

The dyes of this invention are also advantageously incorporated indirect positive emulsions of the type in which a silver halide grain hasa Water-insoluble silver salt center and an outer shell composed of afogged water-insoluble silver salt that develops to silver withoutexposure. The dyes of the invention are incorporated, preferably, in theouter shell of such emulsions. These emulsions can be prepared invarious ways such as those described in Berriman U.S. patent applicationSer. No. 448,467, filed Apr. 15, 1965, now US. Pat. 3,367,778 issuedFeb. 6, 1968. For example, the shell of the grains in such emulsions maybe prepared by precipitating over the core grains a light-sensitivewater-insoluble silver salt that can be fogged and which fog isremovable by bleaching. The shell is of sufficient thickness to preventaccess of the developer used in processing the emulsions of theinvention to the core. The silver salt shell is surface fogged to makeit developable to metallic silver with conventional surface imagedeveloping compositions. The silver salt of the shell is sufiicientlyfogged to produce a density of at least about 0.5 when developed for 6minutes at 68 F. in Developer A below when the emulsion is coated at asilver coverage of mg. per square foot. Such fogging can be effected bychemically sensitizing to fog with the sensitizing agents described forchemically sensitizing the core emulsion, high intensity light and thelike fogging means well known to those skilled in the art. While thecore need not be sensitized to fog, the shell is fogged. Fogging bymeans of a reduction sensitizer, a noble metal salt such as gold saltplus a reduction sensitizer, a sulfur sensitizer, high pH and low pAgsilver halide precipitating conditions, and the like can be suitablyutilized. The shell portion of the subject grains can also be coatedprior to fogging.

DEVELOPER A Grams N-methyl-p-aminophenol sulfate 2.5 Ascorbic acid 10.0Potassium metaborate 35.0 Potassium bromide 1.0

Water to 1 liter. pH of 9.6.

Before the shell of water-insoluble silver salt is added to the silversalt core, the core emulsions are first chemically or physically treatedby methods previously described in the prior art to produce centerswhich promote the deposition of photolytic silver, i.e., latent imagenucleating centers. Such centers can be obtained by various techniquesas described herein. Chemical sensitization techniques of the typedescribed by Antoine Hautot and Henri Saubeneir in Science et IndustriesPhotographiques, vol. XXVIII, January 1957, pages 1 to 23 and January1957, pages 57 to 65 are particularly useful. Such chemicalsensitization includes three major classes, namely, gold or noble metalsensitization, sulfur sensitization,

such as by a labile sulfur compound and reduction sensitization, e.g.,treatment of the silver halide with a strong reducing agent whichintroduces small specks of metallic silver into the silver salt crystalor grain.

The preferred merocyanine dye salts of this invention are highly usefulelectron acceptors in high speed direct positive emulsions comprisingfogged silver halide grains and a compound which accepts electrons, asdescribed and claimed in Illingsworth US. patent application Ser. No.609,794, now abandoned, filed Jan. 17, 1967 and titled PhotographicReversal Materials 111. The fogged silver halide grains of suchemulsions are such that a test portion thereof, when coated as aphotographic silver halide emulsion on a support to give a maximumdensity or at least about one upon processing for six minutes at about68 F. in Kodak DK-SO developer, has a maximum density which is at leastabout 30% greater than the maximum density of an identical coated testportion which is processed for six minutes at about 68 F. in Kodak DK50developer after being bleached for about 10 minutes at about 68 F. in ableach composition of:

Potassium cyanide mg 50 Acetic acid (glacial) cc 3.47 Sodium acetate g11.49 Potassium bromide mg 119 Water to 1 liter.

The grains of such emulsions will lose at least about 25% and generallyat least about 40% of their fog when bleached for ten minutes at 68 F.in a potassium cyanide bleach composition is described herein. This fogloss can'be illustrated by coating the silver halide grains as aphotographic silver halide emulsion on a support to give a maximumdensity of at least 1.0 upon processing for six minutes at about 68 F.in Kodak DK-SO developer and comparing the density of such a coatingwith an identical coating which is processed for six minutes at 68 F. inKodak DK-SO developer after being bleached for about 10 minutes at 68 F.in the potassium cyanide bleach composition. As already indicated, themaximum density of the unbleached coating will be at least 30% greater,generally at least 60% greater, than the maximum density of the bleachedcoating.

The silver halides employed in the preparation of the photographicemulsions useful herein include any of the photographic silver halidesas exemplified by silver bromide, silver iodide, silver chloride, silverchlorobromide, silver bromoiodide, silver chlorobromide, and the like.Silver halide grains having an average grain size less than one micron,preferably less than about 0.5 micron, give particularly good results.The silver halide grains can be regular and can be any suitable shapesuch as cubic or octahedral, as described and claimed in IllingsworthUS. patent application Ser. No. 609,778, now abandoned, filed Jan. 17,1967, and titled Direct Positive Photographic Emulsions I. Such grainsadvantageously have a rather uniform diameter frequency distribution, asdescribed and claimed in Illingsworth US. patent application Ser. No.609,790, now abandoned, filed Jan. 17, 1967, and titled PhotographicReversal Emulsions II. For example, at least 95%, by weight of thephotographic silver halide grains can have a diameter which is withinabout 40%, preferably within about 30% of the mean grain diameter. Meansgrain diameter, i.e., average grain size, can be determined usingconventional methods, e.g., as shown in an article by Trivelli and Smithentitled Empirical Relations Between Sensitometric and Size-FrequencyCharacteristics in Photographic Emulsion Series in The PhotographicJournal, vol. LXXIX, 1949, pages 330-338. The fogged silver halidegrains in these direct-positive photographic emulsions of this inventionproduce a density of at least 0.5 when developed without exposure forfive minutes at 68 F. in Kodak DK-SO developer when such an emulsion iscoated at a coverage of 50 to about 500 mg. of silver per square foot ofsupport. The preferred photographic silver halide emulsions comprise atleast 50 mole percent bromide, the most preferred emulsions being silverbromoiodide emulsions, particularly those containing less than about tenmole percent iodide. The photographic silver halides can be coated atsilver coverages in the range of about 50 to about 500 milligrams ofsilver per square foot of support.

In the preparation of the above photographic emulsions, the preferredmerocyanine dye salts, reducing agents and metal compounds of theinvention are advantageously incorporated in the washed, finished silverhalide emulsion and should, of course, be uniformly distributedthroughout the emulsion. The methods of incorporating dye and otheraddenda in emulsions are relatively simple and well known to thoseskilled in the art of emulsion making. For example, it is convenient toadd them from solutions in appropriate solvents, in which case thesolvent selected should be completely free from any deleterious effecton the ultimate light-sensitive materials. Methanol, isopropanol,pyridine, water, etc., alone or in admixtures, have proven satisfactoryas solvents for this purpose. The type of silver halide emulsions thatcan be sensitized with the new dyes include any of those prepared withhydrophilic colloids that are known to be satisfactory for dispersingsilver halides, for example, emulsions comprising natural materials suchas gelatin, albumin, agar-agar, gum arabic, alginic acid, etc. andhydrophilic synthetic resins such as polyvinyl alcohol,polyvinylpyrrolidone, cellulose ethers, partially hydrolyzed celluloseacetate, and the like.

The preferred merocyanine dye salts, reducing agents and metal compoundsof the invention can be used with emulsions prepared with any of thelight-sensitive silver halide salts including silver chloride, silverbromide, silver chlorobromide, silver bromoiodide, silverchlorobromoiodide, etc. Particularly useful for direct positive foggedemulsions in which the silver salt is a silver bromohalide comprisingmore than 50 mole percent bromide. As indicated previously, the dyes ofthis invention are also useful in emulsions which contain color formers.This is unexpected since related prior art dyes cannot be used inemulsions containing a color former.

The novel emulsions of this invention may be coated on any suitablephotographic support, such as glass, film base such as celluloseacetate, cellulose acetate butyrate, polyesters such as polyethyleneterephthalate, paper, baryta coated paper, polyolefin coated paper,e.g., polyethylene or polypropylene coated paper, which may be electronbombarded to promote emulsion adhesion to produce the novel photographicelements of the invention.

The invention is further illustrated by the following examples. The dyesof Examples 1-7 are especially useful filter dyes.

EXAMPLE 1 Bis 3- (4-fluorosulfonylanilino 1- 2,4,6-trichlorophenyl)4-(2-pyrazolin-5-one) ]trimethine oxonol A mixture of 3.15 g. (2 mols.)of 3-(4-fluorosulfonylanilino -1- (2,4,6-trichlorophenyl)-2-pyrazolin-5-one, 1.0 g. (1 mol. excess) of trimethoxypropene and 0.75g. (1 mol. 100% excess) of triethylamine was heated in 25 ml. of ethanolat the refluxing temperature 9 for 10 minutes. The reaction mixture waspoured into A mixture of 1.8 g. (1 mol.) of 3-(cyanoanilino)-1- waterand the whole made acidic with conc. HCl. The re(2,4,6-trichlorophenyl)-2-pyrazolin-5-one, 2.3 g. (1 mol.) sultingprecipitate was collected and purified by dissolvof2-(Z-acetanilidovinyl)-3-ethylbenzothiazolium iodide ing it in methanolcontaining triethylamine. The solution and 0.6 g. (lmol. 10% excess) oftriethylamine was was filtered and the dye was precipitated by theaddition heated in ml. of ethanol at the refluxing temperature of waterand enough conc. HCl to make the solution 5 for 10 minutes. The reactionmixture was chilled and the acidic. The yield of dark red crystals was59% and they solid collected. The crude dye was purified by dissolvinghad a melting point of 222227 C. with decomposition. the crystals in hotpyridine, filtering the hot solution,

EXAMPLE 2 adding methanol to the solution, chilling the mixture andcollecting the dye. After another like treatment, the yield1315B(3'mtroaPlhno)'1'(z46'mcmorophenyl)4'(2' 10 of dark red crystalswas 68% and they had a melting PYIaZ1m-5'ne)lpentamethme point of262-263 c. with decomposition.

N02 NO2 A mixture of 4.0 g. (2 mols.) of 3-(3-nitroanilino)- EXAMPLE 41-(2,4,6-trich1orophenyl)-3-pyrazolin-S-one, 1.5 g. (1

3-(4-chloroan1l1no)-4-[(3-ethy1-2-benzoth1azolmylidene) mol.) ofglutacomc aldehyde d1an1l hydrochloride and ethylidene] 1 (zmitrophenyl)z pyrazolin s one 1.2 g. (2 mol. +10% excess) of triethylamine washeated in 25 ml. of ethanol at the refluxing temperature for 10 minutes.The reaction mixture was cooled, and enough conc. HCl was added to makethe solution acidic. The l precipitate was collected on a filter and itwas washed y with methanol. The solid was dissolved in methanolcontaining approximately 5 ml. of triethylamine, the solu- NH tion wasfiltered and conc. HCl was added to the filtrate CZHS until it wasacidic. The resulting solid was collected and the above treatment wasrepeated. The yield of dark l crystals was 31% and they had a meltingrange of 209- 216 C., with decomposition. J

In place of the trimethoxypropene in above Example 1, 1

and in place of the glutaconic aldehyde dianilhydrochloride in aboveExample 2, there can be substituted an In a, manner similar to Example3, Example 4 was pre. equivalent amount of diethoxymethyl acetate togive the pared from 1,6 1 1 f 3- 4- 1 1 2- corresponding dye compoundsbis[3-(4-fluorosulfonyl nitro henyl)-2-pyrazolin-5-one and 2.3 g. (1mol.) of 2- P Y -PY (Z-acetanilidovinyl)-3-ethylbenzothiazolium iodide.The methine oxonol and iS[3-( yield of shiny brown needles was 81% andthey had a chlorophenyl)-4-(2-pyrazolin-5-one)]rnethine oxonol,remelting point of 174-175 C., with decomposition. spectively. Theoxonol dyes 0f the above described ex- In place of the 2 (2acetanilidovinyl) 3 ethylamples were found to be excellent filter y in Pt benzothiazolium iodide in the above Examples 3 and 4, graphic filterlayers. there can be substituted an equivalent amount of other EXAMPLE 3related intermediate compounds defined by Formula 1V above, such as3-alkyl (e.g., methyl, ethyl, propyl, ism3-(4-chloroanilino)-4-[(3-ethyl-2-benzothiazolinylidene) PFOPYL butyl, Pdecyl, dodecyl, etcJ-z-(z-acetamlt v1nyl)benzothrazohurn quaternarysalt, e.g., the chlorlde, ethyhdme]-1 (246'mch1orp henyl) 2 pyrazolin 5bromide, iodide, perchlorate, etc. salts, or a 3-alkyl (e.g., onemethyl, ethyl, propyl, isopropyl, butyl, hexyl, decyl, dodecyl, etc.) (2acetanilidovinyl) benzoselenazolium quaternary salt, e.g., the chloride,bromide, iodide, per- 01 chlorate, p-toluenesulfonate, etc. salts, andthe like, to

give the corresponding merocyanine dyes having general- S 1y similarproperties as photographic filter dyes, for example, the dye 3 (4cyanoanilino-4-[(3-methyl-2- N 5, benzothiazolinylidene)ethylidene] 1(2,4,6 trichlorophenyl) 2 pyraZolin-5-one, the dye 3-(4-chloroanilin0)-4 [(3 ethyl 2 benzoselenazolinylidene)ethylidene1- 31 5 1 (2nitrophenyl) 2 pyrazolin 5 one, etc. Also, in place of the 2 pyrazolin 5one intermediates in the above example, there can be substitutedequivalent amounts of any other of the compounds defined by Formula Vabove to give the corresponding merocyanine photographic filter dyes.

1 1 EXAMPLE 5 3 (4 cyanoanilino) 4 [(1,3-diethyl-2(1H)-imidazo- [4,5b]quinoxalinylidene)ethylidene]1-(2,4,6-trichlorophenyl)-2-pyrazolin-5-one A mixture of 2.4 g. (1 mol.)of 4-anilinomethylene- 3 (4 cyanoanilino) 1 (2,4,6 trichlorophenyl)-2-pyrazolin 5 one, 1.8 g. (1 mol.) of 1,3-diethyl-2-methylimidazo[4,5-b1quinoxalinium iodide and 0.6 g. (1 mol.+l% excess)of triethylamine was heated in 25 ml. of acetic anhydride at therefluxing temperature for minutes. The reaction mixture was concentratedto dryness using a rotary evaporator and the residue was stirred inmethanol until crystalline. The crude dye was purified by dissolving itin hot pyridine, filtering the hot solution, adding methanol to thesolution, chilling the mixture and collecting the solid. After anotherlike treatment, the yield of dark red crystals with a green reflex was23% and they had a melting point of 298-299 C., with decomposition.

EXAMPLE 6 3 acetamido 4 [(1,3 diethyl 2(1H)-imidazo- [4,5bJquinoxalinylidene)ethylidene] 1 phenyl-2- pyrazolin-S-one In a mannersimilar to Example 5, Example 6 was prepared from 1.6 g. (1 mol.) of 3acetamido 4 anilinomethylene 1 phenyl 2 pyrazolin 5 one and 2.1 g. (1mol.) of 1,3 diethyl 2 methylimidazo[4,5-b] quinoxaliniump-toluenesulfonate. The yield of deep red crystals with a shiny reflexwas 39% and they had a melting point of 263-264 C., with decomposition.

(EXAMPLE 7 3 anilino 4-[(l,3 diethyl 2-(1H)-imidazo[4,5-b]quinoxalinylidene)ethylidene]-l phenyl 2-pyrazolin- 5-one In a mannersimilar to Example 5, Example 7 was prepared from 3.5 g. (1 mol.) of3-anilino-4-anilinomethylene 1 phenyl 2 pyrazolin-S-one and 2.7 g. (1mol.) of 1,3 diethyl 2 methylimidazo[4,5-b] quinoxalinium chloride. Theyield of dark red crystals with a blue reflex was 36% and they had amelting point of 212214 C., with decomposition.

In place of the 1,3 diethyl 2 methylimidazo[4,5-b] quinoxalinium saltsin the above Examples 5, 6 and 7, there can be substituted an equivalentamount of other related intermediate compounds defined by Formula IVabove such as the 1,3-dialkyl, diaryl or dialkenyl (e.g., methyl, ethyl,propyl, isopropyl, butyl, hexyl, decyl, dodecyl, phenyl, allyl,2-propenyl, etc.) 2 methylimidazo- [4,5-b1quinoxalinium salts, or thechloro-, dichloro-, nitro-, etc. derivatives substituted in the 6- and7-positions thereof, and the like, to give the corresponding merocyaninedyes having generally similar properties as photographic filter dyes,for example, the dye 3 (4-cyanoanilino) 4 [(1,3 diallyl2(1H)-imidazo[4,5-b] quiuoxalinylidene)ethylidene] 1 (2,4,6trichlorophenyl) 2 pyrazolin 5 one, the dye 3-acetamido-4- [(6 chloro1,3 diphenyl 2(1H)-imidazo[4,5-b] quinoxalinylidene)ethylidene] 1 phenyl2 pyrazolin- 5-one, the dye 3 anilino 4 [(l,3 diethyl 6 nitro- 2(1H)imidazo[4,5-b]quinoxalinylidene) ethylidene]-1-phenyl-2-pyrazoline-5-one, etc. Also, in place of the 2- pyrazolin-S-oneintermediates in the above examples, there can be substituted equivalentamount of any other of the compounds defined by Formula V above to givethe corresponding merocyanine photographic filter dyes.

EXAMPLE 8 2 [2 (3 anilino 2 methyl 5 oxo-1-phenyl-3- pyrazolin 4yl)vinyl] 1,3 diethylimidazo[4,5-b] quinoxalinium iodide A mixture of1.4 g. (1 mol.) of 3-anilino-4-[(1,3-diethyl 2(1H)imidazo[4,5-b]quinoxalinylidene)ethyli- .dene] 1 phenyl 2 pyrazolin 5'one (dye of Example 7) and approximately 1 ml. of freshly distilleddimethylsulfate was heated to 150 C., then cooled and the viscous liquidwas stirred in several portions of ether. The residue was dissolved inacetone and the solution was poured into aqueous potassium iodide. Theresulting precipitate was collected and dried. The crude dye wasrecrystallized from 10 ml. of ethanol. The solid was again dissolved in10 ml. of hot ethanol, and after chilling, the solution was filtered,approximately ml. of ether was added to the filtrate, and theprecipitate was collected on a filter. The yield of orange-red crystalswas 18 and they had a melting point of 166-172 C., with decomposition.

The above prepared dye containing the desensitizing 1,3diethylinu'daZo[4,5-b] quinoxaline nucleus is photographically testedfor its usefulness as an electron acceptor and spectral sensitizer forfogged direct positive photographic silver halide emulsions by thefollowing procedure.

A gelatin silver bromoiodide emulsion (2.5 mole percent of the halidebeing iodide) and having an average grain size of about 0.2 micron isprepared by adding an aqueous solution of potassium bromide andpotassium iodide, and an aqueous solution of silver nitrate,simultaneously to a rapidly agitated aqueous gelatin solution at atemperature of 70 C., over a period of about 35 minutes. The emulsion ischill-set, shredded and washed by leaching with cold water in theconventional manner. The emulsion is reduction-gold fogged by firstadding 0.2 mg. of thiourea dioxide per mole of silver and heating for 60minutes at 65 C. and then adding 4.0 mg. of potassium chloroaurate permole of silver and heating for 60 minutes at 65 C. The dye of the aboveexample, 2-[2-(3- anilino-2-methy1-5-oxo 1 phenyl 3 pyrazolin-4-yl)vinyl]-l,3-diethylimidazo[4,5-b]quinoxalinium iodide, is then added tothe above fogged emulsion in amount suili cient to give a concentrationof 008 gram of the dye per mole of silver. The resulting emulsion iscoated on a cellulose acetate film support at a coverage of 100 mg. ofsilver and 400 mg. of gelatin per square foot of support.

A sample of the coated support is then exposed on an Eastman Ibsensitometer using a tungsten light source and processed for 6 minutesat room temperature in Kodak D-l9 developer which has the followingcomposition:

Water to make 1.0 liter.

then fixed, washed and dried. The results are listed in Table Ihereinafter. Referring thereto, it will be seen that the dye of thisexample has a maximum density in the unexposed areas of 1.78 and aminimum density in exposed areas of 0.05, a maximum sensitivity of 510nm. and a relative speed of 263. This result indicates that the dyecompound of the above example is well suited to function as both anelectron acceptor and spectral sensitizer. It thus provides excellentquality direct positive photographic silver halide emulsions. Excellentmagenta images are obtained when the color former1-(2,4,6-trichlorophenyl)-3-{3-[(2,4 ditertpentylphenoxy)acetamido]benzamido}-2-pyrazolin-5-one is incorporatedin the emulsion of this example, the emulsion is coated on a support,exposed to a tungsten source through Wratten filter No. 61 and No. 16,and reversal processed as described in Graham et al. U.S. Pat.3,046,129, issued July 24, 1962, in Example (a) C01. 27, lines 27 etseq. except that black-and-white (MQ) development is omitted, the colordevelopment is reduced to one minute and is conducted in total darknessuntil after fixing.

EXAMPLE 9 2 [2-(3-acetamido-2-methyl-5-oxo-l-phenyl-3-pyrazolin-4-yl)vinyl] 1,3 diethylimidazo[4,5-b]quinoxalinium A mixture of 0.7 (1mol.) of 3-acetamido-4-[( 1,3-diethyl 2(1H)imidazo[4,5-b]quinoxalinylidene)ethylidene1-1-phenyl-2-pyrazolin-5-one(dye of Example 6) and approximately 1 ml. of freshly distilleddimethylsulfate was heated to 150 C., the reaction mixture was thencooled and the viscous liquid was stirred in acetone, the suspension wasfiltered and the filtrate was chilled and the solid collected. After tworecrystallizations from ethanol (50 ml./g.), the yield of brownishcrystals was 10% and they had a melting point of 247-248 C., withdecomposition.

The above dye containing the desensitizing1,3-diethylimidazo[4,5-b]quinoxaline nucleus was photographically testedby the exact procedure described in above Example 8. The results asshown in Table 1 hereinafter indicate that this dye is an excellentelectron acceptor for fogged direct positive photographic emulsionsshowing densities of 1.86 and 0.10 for the unexposed and exposed areas,respectively. However, the relative speed of 138 is somewhat lower thanthat of the other dyes listed in the table.

14 EXAMPLE 10 2-{2-[3-(4-cyanoanilino)-2-methyl 5oxo-l-(2,4,6-trichlorophenyl)-3-pyrazolin 4 yl]vinyl} 1,3diethylirnidazo[4,5-b] quinoxalinium iodide A mixture of 1.5 g. (1 mol.)of 3-(4-cyanoanilino)-4- [(1,3-diethyl 2(1H)imidazo[4,5-b]quinoxalinylidene) ethylidene]-1-(2,4,6-trichlorophenyl) 2pyrazolin-S-one (dye of Example 5) and approximately 2 ml. of freshlydistilled dimethylsulfate was heated to 150. The reaction mixture wascooled, the viscous liquid was stirred in ether, the ether was decantedand the residue was dissolved in acetone. The acetone solution waspoured into aqueous potassium iodide and the precipitate was collectedon a filter. After two recrystallizations from ethanol (50 ml./g.), theyield of red crystals was 6% and they had a melting point of 196197 C.,with decomposition.

The above dye containing the desensitizing1,3-diethylimidazo[4,5-b]quinoxaline nucleus was tested by the exactprocedure in above Example 8. The results in Table 1 hereinafter showdensities of 1.69 and 0.09 in the unexposed and exposed areas,respectively, and a moderately good speed of 191, thereby indicatingthat the dye of this example is an excellent electron acceptor forfogged direct positive photographic emulsions.

EXAMPLE 11 2-{2-[3-(4-cyanoanilino)-2-methyl-5-oxo 1 (2,4,6trichlorophenyl)-3-pyrazolin-4-yl]vinyl} 3 ethylbenzothiazoliump-toluenesulfonate A mixture of 1.0 g. (1 mol.) of 3-(4-cyanoanilino)-4-[(3-ethyl 2 benzothiazolinylidene)ethylidene]-1-(2,4,6-trichlorophenyl)-2-pyrazolin-5-one (dye of Example 3) andapproximately 1 ml. of methyl p-toluenesulfonate was heated to C. Thereaction mixture was cooled, the viscous liquid was stirred in ether,the ether was decanted, the residue was stirred in acetone untilcrystalline and the solid was collected on a filter. The yield of orangecrystals, after two recrystallizations from methanol (30 ml./ g.), was60% and they had a melting point of 278-281" C., with decomposition.

The photographic testing of the above prepared dye containing thesensitizing 3-ethyl-2-bcnzothiazole nucleus was carried out by the exactprocedure described in above Example 8. The results as shown in Table lhereinafter of densities of 1.72 and 0.03 in the unexposed and exposedareas, respectively with maximum sensitivity at 495 nm. and a relativespeed of 692, indicate that the above dye is an outstanding electronacceptor and spectral sensitizer for fogged direct positive photographicemulsions.

EXAMPLE 12 2-{2-[3-(4-chloroanilino) 2 methyl-1-(2-nitrophenyl)--oxo-3-pyrazolin 4 yl]vinyl}-3-ethylbenzothiazolium p-toluenesulfonate Amixture of 1.0 g. (1 mol.) of 3-(4-chloroanilino)-4- [(3-ethyl 2benzothiazolinylidene)ethylidene]-1-(2-nitro phenyl)-2-pyrazolin-5-one(dye of Example 4) and approximately 1 ml. of methyl p-toluenesulfonatewas treated as in Example 4. The yield of orange crystals was 65% andthey had a melting point of 177-178 C.

The above prepared dye containing the sensitizing 3-ethyl-Z-benzothiazole nucleus was photographically tested by the exactprocedure described in above Example 8. The results as shown in Table 1hereinafter of densities of 1.72 and 0.04 in the unexposed and exposedareas, respectively, with maximum sensitivity at 510 nm. and a relativespeed of 398, indicate that the above dye is also an outstandingelectron acceptor and spectral sensitizer for fogged direct positivephotographic emulsions.

It will be apparent from the foregoing that the intermediates employedin above Examples 8 to 12, inclusive, can be substituted by any other ofthose defined by Formula II above to give still other relatedmerocyanine dye salts having generally similar properties as electronacceptors and spectral sensitizers for fogged photographic reversalemulsions, for example, the dye 2-[2-(3-anilino- Z-methyl 5 oxo 1phenyl-3-pyrazolin-4-yl)vinyl]-6-chloro-1,3-diethylimidazo[4,5-b1quinoxalinium salt (quaternary salt, forexample, the chloride, bromide, iodide, perchlorate, p-toluenesulfonate,etc., salt; the dye 1,3-diallyl-2-[2-(3 anilirro 2methyl-S-oxo-l-phenyl-3-pyrazolin 4 yl)vinyl]imidazo[4,5-b]quinoxaliniumsalt; the dye 2-[2-(3-acetamido 2 methyl 5 oxo-l-phenyl-3-pyrazolin-4-yl)vinyl]-1,3-diethyl 6 nitroimidazo [4,S-b] quinoxaliniumsalt; the dye 1,3-dibutyl-2-[2-(2-methyl-5-oxo-1-phenyl-3-propionamido-3-pyrazolin 4 yl)vinyl]- imidazo[4,5-b]quinoxalinium salt; the dye 5,6-dichloro-2-{2-[3-(4-cyanoanilino)-2-mcthyl 5 oxo 1(2,4,6-trichlorophenyl)-3-pyrazolin 4yl]vinyl}-1,3-diethylimidaZo[4,5-b]quinoxalinium salt, and the like; thedye 2-{2- [3-(4-cyanoanilino)-2-methy1 5 oxo-l-(2,4,6-trichlorophenyl)3-pyraZolin-4-yl]vinyl}-3-ethyl 6 nitrobenzothiazolium salt; the dye3-ethyl-2-{2-[3-(4-fluorosulfonylanilino) 2 methyl 5oxo-1-(2,4,6-trichlorophenyl)-3-pyrazolin-4-yl]vinyl}-5-nitrobenzoxazolium salt; the dye2-{2-[3-(4-chloroanilino)-2-methyl 1 (2-nitrophenyl)- 5-oxo 3pyrazolin-4-yl]vinyl}-3-ethyl 6 nitrobenzoselenazolium salt, and thelike.

The following Examples 13-15 illustrates the preparation of some of theintermediates employed in the preceding examples to prepare the dyecompounds of the invention.

16 EXAMPLE 134-anilinomethylene-3-(4-cyanoanilino)-1-(2,4,6-trichlorophenyl)-2-pyrazolin-5-one I IYIH I ON A mixture of 7.3 g. (1 mol.) of3-(4-cyanoanilino)-l- (2,4,6-trichlorophenyl)-2-pyrazolin-5-one and 3.3g. (1 mol.+10% excess) of ethyl isoformanilide was heated in 50 ml. ofethanol at the refluxing temperature for 1 hr. The reaction mixture waschilled, the resulting solid was collected on a filter and washed withethanol. The yield of yellow crystals was 71% EXAMPLE 143-acetamido-4-anilinomethylenel-phenyl- Z-pyrazolin-S-one m roo CH3 Amixture of 1.8 g. (1 mol.) of 3-acetamido-1-phenyl- 2pyrazolin-5-one and1.4 g. (1 mol.+ 10% excess) of ethyl isoformanilide was heated in 10 ml.of ethanol for 1 minute. The reaction mixture was chilled, the resultingsolid was collected on a filter and washed with ethanol. The yield ofbright yellow crystals was 71% EXAMPLE 15 the exact procedure describedin above Example 8. The

results are listed in the following table.

TABLE I Density Dye cone, Relative Max. Min. Sensitizg./mole clearunexposed exposed ing max. silver speed areas areas (nm.)

1 No dye.

2 No reversal.

The following examples further illustrate the preparation of fogged,direct positive photographic emulsions and elements with the cyaninedyes of the invention.

EXAMPLE 16 Grams N-methyl-p-aminophenol sulfate 3.1 Sodium sulfite, des45 Hydroquinone 12 Sodium carbonate, des 67.5 Potassium bromide 1.9

Water to 1 liter.

The light fogged material can be exposed to an image with lightmodulated by a Wratten No. 15 filter to give a direct positive image.Generally similar results are obtained when the dye of Example 10 isused in place of the above dye.

EXAMPLE 17 Seven pounds of a silver chloride gelatin emulsion containingthe equivalent of 100 g. of silver nitrate is heated to 40 C. and the pHis adjusted to 7.8. Eight cc. of full strength (40%) formalin solutionis added and the emulsion is held at 40 C. for 10 minutes. At the end ofthe holding period, the pH is adjusted to 6.0 and 0.125 g. of 2 {2 [3 (4cyanoanilino) 2 methyl 5 oxo l- (2,4,6-trichlorophenyl) 3 pyrazolin4-yl]vinyl} 3- ethylbenzothiazolium p-toluenesulfonate (Example 11). Theemulsion is coated on a support, and provides good direct positiveimages. Similar results are obtained when the dye of Example 12 issubstituted for the above dye.

By substituting other dye compounds of the invention, as defined inFormula I above, into the procedure of the above Examples 16 and 17,similar fogged, direct positive photographic silver halide emulsions andphotographic elements may be prepared.

The photographic silver halide emulsion and other layers present in thephotographic elements made according to the invention can be hardenedwith any suitable hardener, including aldehyde hardeners such asformaldehyde, and mucochloric acid, aziridine hardeners, hardeners whichare derivatives of dioxane, oxypolysaccharides such as oxy starch or oxyplant gums, and the like. The emulsion layers can also containadditional additives, particularly those known to be beneficial inphotographic emulsions, including, for example, lubricating materials,stabilizers, speed increasing materials, absorbing dyes, plasticizers,and the like. These photographic emulsions can also contain in somecases additional spectral sensitizing dyes. Furthermore, these emulsionscan contain color forming couplers or can be developed in solutionscontaining couplers or other color generating materials. Among theuseful color formers are the monomeric and polymeric color formers,e.g., pyrazolone color formers, as well as phenolic, heterocyclic andopen chain couplers having a reactive methylene group. The color formingcouplers can be incorporated into the direct positive photographicsilver halide emulsion using any suitable technique, e.g., techniques ofthe type shown in Jelley et al. US. Pat. 2,322,027, issued June 15,1943, Fierke et al., US. Pat. 2,801,171, issued July 30, 1957, FisherU.S. Pats. 1,055,155 and 1,102,028, issued Mar. 4, 1913 and June 30,1914, respectively, and Wilmanns U.S. Pat. 2,186,849 issued Jan. 9,1940. They can also be developed using incorporated developers such aspolyhydroxybenzenes, aminophenols, 3-pyrazolidones, and the like.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof, it willbe understood that variat ions and modifications can be effected withinthe spirit and scope of the invention as described hereinabove, and asdefined in the appended claims.

I claim:

1. A dye selected from those having one of the following formulas:

0=o--N-R,

| NH-Ra 1 111-188 wherein m and n each represents a positive integer offrom 1 to 2; d represents a positive integer of from 1 to 3; Lrepresents a methine linkage; R represents a member selected from thegroup consisting of an alkyl group of 1 to 4 carbon atoms, an alkenylgroup of 1 to 4 carbon atoms and an aryl group of 6 to 20 carbon atoms;R rep resents an alkyl group of 1 to 4 carbon atoms or an alkenyl groupof 1 to 4 carbon atoms; R represents an alkyl group of 1 to 4 carbonatoms or an aryl group of 6 to 20 carbon atoms; R represents a memberselected from the group consisting of an aryl group of 6 to 20 carbonatoms and the group COR wherein R represents an alkyl group of 1 to 4carbon atoms; X represents an acid anion selected from chloride,bromide, iodide, thiocyanate, sulfamate, perchlorate,p-toluenesulfonate, methyl sulfate and ethyl sulfate; and Z represents anucleus selected from the group consisting of a thiazole nucleus, anoxazole nucleus, a selenazole nucleus, a thiazoline nucleus, a pyridinenucleus, a quinoline nucleus, and an imidazole nucleus.

2. A merocyanine dye represented by the following formula:

wherein n and m each represents a positive integer of from 1 to 2; Lrepresents a methine linkage; R represents a member selected from thegroup consisting of an alkyl group of l to 4 carbon atoms, an alkenylgroup of l to 4 carbon atoms and an aryl group of 6 to 20 carbon atoms;R represents an alkyl group of 1 to 4 carbon atoms or an alkenyl groupof 1 to 4 carbon atoms, R represents an alkyl group of 1 to 4 carbonatoms or an aryl group of 6 to 20 carbon atoms; R represents a memberselected from the group consisting of an aryl group of 6 to 20 carbonatoms and the group -COR wherein R represents an alkyl group of 1 to 4carbon atoms; X represents an acid anion selected from chloride,bromide, iodide, thiocyanate, sulfamate, perchlorate,p-toluenesulfonate, methyl sulfate and ethyl sulfate and Z represents anucleus selected from the group consisting of a thiazole nucleus, anoxazole nucleus, a selenazole nucleus, a thiazoline nucleus, a pyridinenucleus, a quinoline nucleus, and an imidazole nucleus.

3. A dye as defined by claim 2 wherein said m is 2.

4. A dye as defined by claim 2 wherein said Z in animidazo[4,5-b1quinoxaline nucleus.

5. A dye as defined by claim 2 wherein said Z is a thiazole nucleus.

6. A dye selected from the group consisting of 2-[2-(3- anilino 2 methyl5 0x0 1 phenyl 3 pyrazolin- 19 4 yl) vinyl] 1,3 diethylimidazo[4,5b]quinoxalinium salt; 2-[2-(3-acetamido-2-methyl-5-oxo-1-phenyl-3-pyrazolin 4 yl)vinyl] 1,3 diethylirnidazo[4,5-b]quinoxalinium salt; 2 {2[3 (4-cyanoanilino)-2-methyl-5- x0 1 (2,4,6 trichlorophenyl) 3 pyrazolin4 yl]- vinyl}-1,3-diethylimidaz0[4,5-b] quinoxalinium salt; 2-{2- [3 (4cyanoanilino) 2 methyl 5 oxo 1 (2,4,6- trichlorophenyl) 3 pyrazolin 4yl]vinyl} 3 ethylbenzothiazolium salt; and 2-{2-[3-(4-chloroanilino)-2-methyl 1 (2 nitrophenyl) 5 0x0 3 pyrazolin 4-yl]viny1}-3-ethy1benzothiazolium salt.

7. An oxonol dye having the formula:

Rz-l]I--(|J=O H0C--(I3--Rg N G=CH(L=L)d-1 N 0 I NH-Rg NH-R; wherein [Zrepresents a positive integer of from 1 to 3; L represents a methinelinkage; R represents an alkyl group of 1 to 4 carbon atoms or an arylgroup of 6 to 20 carbon atoms; R represents a member selected from thegroup References Cited UNITED STATES PATENTS 2,639,282 5/ 1953 Spragueet al 260-2404 2,652,397 9/ 1953 Aubert et a1 260-240.4 2,656,35210/1953 Knott et a1 26'0240.1

JOHN D. RANDOLPH, Primary Examiner US. Cl. X.R.

96107, 139; 260-240.4, 240.8, 283 S, 294.8 G, 298, 304, 306, 306.7, 307D, 309, 310 A, 326.12 R

